EP-A-0726053 discloses a filter holder for espresso machines, comprising a filter-cup housing provided with a bottom and a coffee dispensing aperture through the bottom. This known device further comprises a valve with a valve stopper which selectively closes and opens the dispensing aperture. The stopper is supported by a pivoting arm and is resiliently biased in a closed position. A pivoting cam is located between the bottom of the filter-cup housing and the pivoting arm of the stopper, for preventing the stopper from closing in certain operating conditions. The valve closes the dispensing aperture before starting a brewing cycle, preventing coffee from flowing through the filter until a sufficient brewing pressure builds in the coffee cake. Only upon reaching a brewing pressure, which is determined by the resilient force applied to the valve stopper, the valve opens and coffee is dispensed through the aperture. Once the valve stopper has moved to the open position, the pivoting cam moves in an active position, where it prevents the valve stopper from closing the aperture again.